The manufacturing of semiconductor devices includes the transfer of patterns into the semiconductor wafer in a photolithography process. Shortwave radiation from a laser source passes a photomask or is reflected at a photomask and incidents on a photosensitive layer on the semiconductor wafer. The pattern of the photomask defines the pattern on the semiconductor wafer. There is a need to supply semiconductor manufacturers with photomasks reliably fulfilling imaging specifications with respect to the imaged patterns.